The person should be a male.
Only male carries XY chromosomes, meanwhile female carries XX chromosomes. "Heterozygous for the X and Y chromosomes" means that the person have both X and Y chromosomes in their cells, therefore only males fits the description.
This is also why the birth rate of girl or a boy is always 50%, it is because the sex of a person is only determined by the sperm from a male. Each sperm either carries a X or a Y chromosome, never the both. Therefore, the chances of a X or a Y sperm fertilising an X egg is always 50%, also explains why both female or male must have at least one X chromosome because an egg always carry an X.
Take samples around you and see what bacteria will grow.https://www.stevespanglerscience.com/lab/experiments/growing-bacteria/
Three percent is freshwater found in glaciers and ice, below the ground, or in rivers and lakes.
<span>The answer is enzymes. Enzymes are biological catalysts and increase the speed of change from substrate to product. The name of enzymes is usually derived from the substrate they break down. For example, lactase breaks down sugar lactose. The name of enzymes contains suffix -ase, for instance, carbonic anhydrase, lactase, lipase, amylase, etc...</span>
Its a scientist thing I don't know but it has to do with something in your body
